Find seating depth or powder charge first on VLD's?

[Pdvdh]

First, I have no idea why best seating is prerequisite to best grouping. I just know it is.

When you test for best seating with a method(like Berger's), you'll find good potential and pure ugly and good potential again and ugly again.

Don't try to guess best or 'starting' seating. Find it up front, log it, and stay with it.

Thanks Mike. I will use this method with a rifle I hope to be receiving soon.

 

[mrb1982]

I think Mike has a good explanation there. I have also heard and read of people who have reloaded for a certain caliber in a number of rifles or whatnot and have had good luck with x bullet being seated x from the lands with x grains of powder. So they'll load something like that up for a different rifle and tune from there. Probably works good for them too, but they have by far more reloading experience than I have.

I found that the Berger method being referred to worked pretty good for a novice reloader like myself. I don't do a ton of it and am learning something new about it every day. When I first started the seating test, I was afraid I wouldn't have one that stood out. I had one that was above and beyond the rest. Then I loaded up my powder charges to tune and feel it out.

One thing that I found kind of weird is as I worked my way up in powder charge, my groups started to really open up. I almost quit with on last group of powder charges left. But I thought, hmmm, still no signs of pressure, lets just see what happens with these. Figured I would shoot one at the very least to see if I got pressure signs. Still ended up with no pressure signs, and the groups shrunk right up to where they were at in my seating tests. That was at 1.5gr over max, and I was quite surprised. Didn't feel the need to pour any more powder to it for performance but would have liked to have seen just how high a guy could have went.

I guess the moral of my story on that is just keep pushing through as long as it is safe in the gun. I had a buddy tell me about this happening occasionally with some of his guns where it's good, then it opens up, but then comes back in as he goes up the ladder. Just taught me to make sure I do thorough testing as I would have quit otherwise.

 

[BrentM]

Good info, as usual.

I tend to start around .020 to .050 to find max charge. Then back it off and shoot depth. I reload in the field so I don't waste ammo. Seems to work ok for me. I have 2 rifles that really like .100 off the lands. This is base off of shooting the highest velocity I can safely get away with and then tune for accuracy.

Be cautious, though, seating close or in the lands with a max charge weight at say .050 off. You might have a problem as seating close can and usually does produce high pressure. I chronoed loads with the same charge weight over 6 depths and noticed pressure signs and velocity changes on several calibers.

Based on this I too believe a rifle and bullet have have a sweet spot in regard to seating depth.

 

[Mikecr]

I too believe a rifle and bullet have have a sweet spot in regard to seating depth.

And I hope someday to understand it.
I have read all my life implications of seating as an extension of powder, and yet this flat out fails tests. They truly seem independent and still produce similar results(but separately).
I can make a solid 1/4moa barrel open to +3/4moa with seating adjustment, even when I normalize MV to the adjustment. No amount or type of powder change would affect results so much (300%), but there are also distinct nodes here as well.
When both node types overlap, we call it a great tune.

So given that there are seating nodes, and they hold based on bullet rather than load, what is a seating node causing?
I've wondered if seating is shaping the pressure peak, which could hold unique character of it's own regardless of the curve further produced throughout the full length of bore(normalized).
I'd love to see seating adjustments with a strain gauge/pressure trace on a barrel.

 

[BrentM]

Yep! Ha ha
I read an article that discussed pressure in regard to depth and how pressure builds within the case. This relationship produces pressure spikes and average pressures. It seems the more linear the pressure vs a spike the more accurate the load.

I am no expert but my tune for a lr hunting load is to get the highest possible velocity within the safe pressure level. I then tune for accuracy. Personally I have better results slowing down the velocity and tuning both.
For example my 204 can shoot 3780 to 3800 with different depths but at 1 depth it tightens up. Another example my 6.5 - 284 has an accuracy node around 2750 to 2800 then again at 2950 to 3000. The lower velocity produces a bit better accuracy such as .18 but at 150 fps faster it is .3. I choose .3. Some people would probably disagree with me though.

 

[RustyRick]

I've just gotten back into reloading after some years off. Excited to see how much has changed. Especially in tools, and philosophy's.

So I bought a Hornady Base to Ogive gage. And my micrometer cost me $88 probably 30 yrs ago so it should be a good one.

Now to be the devils advocate.

I find that individual bullets (projectiles) out of the box vary more in length than the seating depths talked about in this forum. I find you can measure the same loaded case and get massive differences in length.

For example I measured 3 groups of 10 loaded cases with 3 different bullets after seating them. I found a STANDARD DEVIATION OF .04115 in one group of ten, .0948 and .0553 in the last group.

I was shocked and left dumfounded. So I phoned one of the bullet manufactures and he freely admitted considerable difference between bullet length even with strict QC.

So my conclusion is that a person is fooling himself some if he put too much stock into calculating seating depth.

 

[mrb1982]

I've just gotten back into reloading after some years off. Excited to see how much has changed. Especially in tools, and philosophy's.

So I bought a Hornady Base to Ogive gage. And my micrometer cost me $88 probably 30 yrs ago so it should be a good one.

Now to be the devils advocate.

I find that individual bullets (projectiles) out of the box vary more in length than the seating depths talked about in this forum. I find you can measure the same loaded case and get massive differences in length.

For example I measured 3 groups of 10 loaded cases with 3 different bullets after seating them. I found a STANDARD DEVIATION OF .04115 in one group of ten, .0948 and .0553 in the last group.

I was shocked and left dumfounded. So I phoned one of the bullet manufactures and he freely admitted considerable difference between bullet length even with strict QC.

So my conclusion is that a person is fooling himself some if he put too much stock into calculating seating depth.

Lol maybe we are all full of crap!!!! hahahaha

 

[twoftagl]

For example I measured 3 groups of 10 loaded cases with 3 different bullets after seating them. I found a STANDARD DEVIATION OF .04115 in one group of ten, .0948 and .0553 in the last group.

So my conclusion is that a person is fooling himself some if he put too much stock into calculating seating depth.

How are you measuring? OAL or base to ogive? And which bullets are you seeing this variation?

Make sure your seating die is not seating by pushing on the tip of the bullet. If it is, this is where your variance is coming from. The seating die should give clearance around the tip and push the bullet more near the ogive where the bullet doesn't vary as much. Pushing on the tip can cause further deformation of a lead, or flex of a polymer tip. Some older dies will do this, as some newer bullets need more clearance to allow for the longer nose.

You should be able to keep the base-to-ogive +\- .001" to .002" without too many troubles.

Chris

 

[Canadian Bushman]

I've just gotten back into reloading after some years off. Excited to see how much has changed. Especially in tools, and philosophy's.

So I bought a Hornady Base to Ogive gage. And my micrometer cost me $88 probably 30 yrs ago so it should be a good one.

Now to be the devils advocate.

I find that individual bullets (projectiles) out of the box vary more in length than the seating depths talked about in this forum. I find you can measure the same loaded case and get massive differences in length.

For example I measured 3 groups of 10 loaded cases with 3 different bullets after seating them. I found a STANDARD DEVIATION OF .04115 in one group of ten, .0948 and .0553 in the last group.

I was shocked and left dumfounded. So I phoned one of the bullet manufactures and he freely admitted considerable difference between bullet length even with strict QC.

So my conclusion is that a person is fooling himself some if he put too much stock into calculating seating depth.

This to me seems strange. Even your low sd of .041" seems really high. With crap bullets i can usually hold +\-.005 and with bergers i have no problem holding +\-.002 usually closer. It would make more sense if you were seating off the tip but it still seems like a lot of variation.

 

[BrentM]

Fooling himself. LOL. OK. Perhaps we should just seat to the manual of your choice depth and use the most accurate powder charge they recommend and leave it all alone. ; )

Now to be serious again.......I have no clue how you could get various readings if you are measuring Base to Ogive. If you are not measuring to the bullets ogive then you are fooling yourself. BULLETS have two main lengths of which you can measure. 1. Overall length of the bullet base to the bullet tip. 2. Bullet base to bullet ogive. IF you have a lot of bullets that are not consistent with the base to Ogive, then likely you have bearing surface issue. To measure that you can run two ogive guages back to back on the bullet and get a bearing surface measurment. If you are really picky you should sort the box of bullets and into lots of same bearing surface.

Now, for proper measurement of the loaded round, you measure ogive of the bullet to the base of the case, and that better be giving you consistent readings. If not, the plunger in your die is probably contacting the tip of the bullet and therefore is not going to work well with VLD style bullets. You can remove the plunger and see if the depth of the plunger nose cone is contacting the ogive or the tip.

Also, if the tip is contacting the plunger it is possible you are not producing straight ammo.

 

[RustyRick]

All good points I'm sure. I think someone earlier thought I was being cheeky. Not so. Just trying to be totally objective.

I'm using Hornady dies with the OGIV sleeve? I like that idea. I'm not a machinist, so I don't know why the variance. However between the shell head holder, the ram action of the loading press and the calipers that we buy off the shelf I'm not sure if we can argue in .001 of an inch or mm.

I just measured 4 Nosler AccuBonds in the 6.5 caliber and 140 grain. I got 5 different measurements 35.60,35.64,35.50,35.48, and 35.57. ??? Sorry Nosler

That's just the projectile out of the new box.

Measure some your selves?

 

[Canadian Bushman]

Rick,
You are measuring in mm. I assumed you were working in inches. Im sorry dude. That was a big misunderstanding. .1mm is actually very small.

 

[Canadian Bushman]

I just measured 4 Nosler AccuBonds in the 6.5 caliber and 140 grain. I got 5 different measurements 35.60,35.64,35.50,35.48, and 35.57. ??? Sorry Nosler

Thats only a dev. of +\-.003 inches. Quite acceptable.
Typically ive found accuracy windows in seating depths to be .01-.030 inches wide. (.3-.8mm)

 

[mrb1982]

I have a set of RCBS Dies that I am loading 180gr Berger Hybrids with. Hopefully my dies are contacting the ogive and not the tip. hmmmmm haven't noticed a lot of variability I guess.